1. Use them for tire liners
One of the best ways to eliminate flats is to take an old worn-out tire and cut off the bead (the stiff edge of the tire that comes in contact with your rim and helps hold the wheel on), as well as the side casing. Then take what's left, essentially the tread, the flat part of the tire that comes in contact with the road and use it as a liner in your regular tire. Use a fairly smooth tire, not a knobby one.
To install, just tuck it inside your good tire, and then insert your good tube, inflating like normal, which will press the old tire inside the new tire up against the tread. You'll then have two layers of rubber that any sharp rocks, glass, wire, whatever will have to penetrate before hitting the tube.
2. Use them around the house for a variety of handy things
Oftentimes, you can find handy uses for old inner tubes around the house if you simply cut them up and use them like you would a bungee cord. You can lash items to your bike rack. Or use them to stake a newly-planted sapling. I slid lengths of inner tube onto the straps of my bike rack where they come in contact with my trunk lid and roof to prevent the coarse straps from rubbing the paint.
Here's an example of a person who stretched bike tubes over furniture legs fastened to the wall to created a functional and handy shelving system. Other people have created rugs and chairs from bike tubes, as well as mirrors and clocks.
3. Transform them into fashion accessories
There are a number of cottage industries that have sprung up in order to take scrap tires and tubes and to make something new from them. For examples, just check out:
- Velo-re, which makes belts, wallets and other items
- Alchemy Goods, and its line of messenger bags, wallets, pouches, belts and more
- Retired Belts - handmade belts made from tires ridden in San Francisco
If you're the crafty type, perhaps you can take your old tubes and tires and come up with something similar.
4. Resurrect them (again)
If there is still any life left in the tubes, you could follow the example of the Boise Bicycle Project, which takes used tubes, patches them and sells them for cheap or gives them to the local refugee population.
There is something noble about keeping a tube in service. I know a guy who takes pride in how many times he can patch a tube. I'm convinced that one of his tubes is not actually a tube any more, just a collection of so many patches that it eventually just subsumed what was once his inner tube. Of course, your safety should be a factor here. Don't be riding around on tires that are in danger of blowing out or that have no tread left.
5. See if your local bike shop can take them
Bike shops will sometimes accept your old tubes and tires for recycling. If they do, sometimes this is free, sometimes there is a small charge. In St. Louis, a unique partnership was created between bike shops and a local sheltered workshop that keeps old rubber out of the landfill and provides meaningful employment for developmentally disabled adults. Since 2007 roughly three tons of tubes and tires have been saved from the landfill.
At the bike shops, tires cost $.50 each to recycle, and tubes are free. The sheltered workshop sorts and stores the loads, then bulk ships them to the recyclers, where they are ground into 'crumb' rubber, used mostly for rubber ground surfaces on playgrounds, artificial turf fields, etc. as well as asphalt.